Multi-stable micro electromechanical switches and methods of fabricating same

ABSTRACT

A micro electromechanical (MEMS) switch suitable for use in medical devices is provided, along with methods of producing and using MEMS switches. In one aspect, a micro electromechanical switch including a moveable member configured to electrically cooperate with a receiving terminal is formed on a substrate. The moveable member and the receiving terminal each include an insulating layer proximate to the substrate and a conducting layer proximate to the insulating layer opposite the substrate. In various embodiments, the conducting layers of the moveable member and/or receiving terminal include a protruding region that extends outward from the substrate to switchably couple the conducting layers of the moveable member and the receiving terminal to thereby form a switch. The switch may be actuated using, for example, electrostatic energy.

CROSS-REFERENCE TO RELATED APPLICATION

This is a divisional application of and claims priority to U.S. Ser. No.11/532,689 filed Sep. 18, 2006; which is a divisional of and claimspriority to U.S. Ser. No. 10/425,861, filed Apr. 29, 2003, now U.S. Pat.No. 7,190,245; incorporated herein by reference in there entireties.

TECHNICAL FIELD

The present invention generally relates to electromechanical switches,and more particularly relates to micro electromechanical switches thathave multiple stable states.

BACKGROUND

Switches are commonly found in most modern electrical and electronicdevices to selectively place electrical, optical and/or other signalsonto desired signal paths. Switches may be used to enable or disablecertain components or circuits operating within a system, for example,or may be used to route communications signals from a sender to areceiver. Electromechanical switches in particular are often found inmedical, industrial, aerospace, consumer electronics and other settings.

In recent years, advances in micro electromechanical systems (MEMS) andother technologies have enabled new generations of electromechanicalswitches that are extremely small (e.g. on the order of micrometers, or10 ⁻⁶ meters) in size. Because many micro switches can be fabricated ona single wafer or substrate, elaborate switching circuits may beconstructed within a relatively small physical space. Although it wouldgenerally be desirable to include such tiny electromagnetic switches inmedical devices (e.g. pacemakers, defibrillators, etc.) and otherapplications, several disadvantages have prevented widespread use inmany products and environments. Most notably, many conventional microelectromechanical switches consume too much power for practical use indemanding environments, such as in a device that is implanted within ahuman body. Moreover, difficulties often arise in isolating the switchactuation signal from the transmitted signal in such environments.Further, the amount of energy (e.g. electrical voltage) typicallyrequired to actuate a conventional electromechanical switch may be toogreat for many practical applications, particularly in the medicalfield.

Accordingly, it is desirable to create a micro electromechanical switchthat consumes a relatively low amount of power, and that can be actuatedwith a relatively small amount of energy. It is also desirable to createan electromechanical switch that improves electrical isolation betweenswitch actuation signals and signals routed by the switch. In addition,it is desirable to create a micro electromechanical switch that iseasily manufactured, and that is suitable for use in demanding medicaldevice applications and the like. Furthermore, other desirable featuresand characteristics of the present invention will become apparent fromthe subsequent detailed description and the appended claims, taken inconjunction with the accompanying drawings and the foregoing technicalfield and background.

BRIEF SUMMARY

In one aspect, a micro electromechanical switch including a moveablemember configured to electrically cooperate with a receiving terminal isformed on a substrate. The moveable member and the receiving terminaleach include an insulating layer proximate to the substrate and aconducting layer proximate to the insulating layer opposite thesubstrate. In various embodiments, the conducting layers of the moveablemember and/or receiving terminal include a protruding region thatextends outward from the substrate to switchably couple the conductinglayers of the moveable member and the receiving terminal to thereby forma switch. The switch may be actuated using, for example, electrostaticenergy.

In a further aspect, a multi-stable electromechanical switch having anopen state and a closed state suitably includes a moveable member and atleast one pair of receiving terminals biased to a bias positioncorresponding to the open state. Each terminal suitably has anoutcropping configured to interface with the moveable member in theclosed state. An actuating circuit provides electrostatic energy todisplace the receiving terminals from the bias position, and to displacethe moveable member toward the bias position. The receiving terminalsthen return toward the bias position when the electrostatic energy isremoved to establish an electrical connection with the moveable member,thereby retaining the electromechanical switch in the closed state.

The various electromechanical switches described herein may be useful ina wide variety of applications, including many applications in themedical device field. Such switches may be useful in producingY-adapter-type lead multiplexers for implantable devices, for example,as well as in producing switchable electrostimulation electrode arraysand the like.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

The present invention will hereinafter be described in conjunction withthe following drawing figures, wherein like numerals denote likeelements, and

FIGS. 1A-B are cross-sectional side views of exemplary opposing contactmembers of an exemplary switch;

FIGS. 2A-D are cross-sectional side views illustrating an exemplaryprocess for producing exemplary contact members;

FIG. 3 is a top view of an exemplary electromechanical switch;

FIG. 4 is a side view of an exemplary electromechanical switch;

FIGS. 5A-C are top views of an exemplary tri-stable microelectromechanical switch; and

FIG. 6 is a top view of an exemplary bi-stable micro electromechanicalswitch with an exemplary actuating circuit.

DETAILED DESCRIPTION

The following detailed description is merely exemplary in nature and isnot intended to limit the invention or the application and uses of theinvention. Furthermore, there is no intention to be bound by anyexpressed or implied theory presented in the preceding technical field,background, brief summary or the following detailed description.

According to various exemplary embodiments, switches suitable for use inmedical devices and the like are fabricated using conventional MEMStechniques. The switches suitably include a moveable armature,cantilever or other member that is capable of selectively engaging oneor more receiving terminals to place the switch into a desired state. Invarious embodiments, the moveable member and/or receiving terminal(s)are fashioned with a protruding region formed of a noble metal (e.g.gold) or another conductive material to improve electrical connectionswithin the switch. In further embodiments, the switch is configured toexhibit two or more stable output states without consuming energy tomaintain the switch in a desired state. Stability is provided bymechanically biasing one or more receiving terminals to a positioncorresponding to a first state of the switch (e.g. an open statecorresponding to an open circuit), and by positioning the moveablemember into the bias position when the switch is in another state (e.g.corresponding to a closed switch). In such embodiments the mechanicalbias of the receiving terminals maintains contact with the moveablemember even when the energy used to displace switch components isremoved. Accordingly, the switch remains in the desired state withoutrequiring continuous application of energy, thereby conserving power.The various switches described herein may be used in a wide variety ofapplications, including applications in the medical, industrial,aerospace, consumer electronic or other arts. Several applications inthe medical field include switchable Y-adapter lead multiplexers forimplantable medical devices, switchable electrode arrays, and the like.

With reference now to FIG. 1A, an exemplary electromechanical switchsuitably includes a moveable member 101 that electrically contacts withone or more receiving terminals 102 to complete an electrical circuit,and to thereby place switch 100 into a desired output state (e.g. openor closed). Moveable member 101 and any associated terminals 102 arecollectively referred to herein as “contact members”. Moveable member101 is suitably formed from a substrate layer 104A, an insulating layer106A, a conducting layer 108A, and a conductive coating 110A thatappropriately surrounds conducting layer 108A to form a protrudingregion 116A that extends radially outward from substrate 104A, and thatprovides an appropriate electrical contact to receiving terminal 102.Similarly, terminal 102 is suitably formed from a substrate layer 104B,an insulating layer 106B, a conducting layer 108B, and a conductivecoating 110B. Conductive coating 110B may also be formed to create aprotruding region 116B extending outward from receiving terminal 102 tointerface with protruding region 116A of moveable member 101 and tothereby form an electrical connection to close switch 100. Although bothmoveable member 101 and terminal 102 are both shown in FIG. 1A withprotruding regions 116, the protruding portion may be removed fromeither of the contact members in various alternate embodiments.

In operation, moveable member 101 is capable of lateral movement toswitchably engage receiving terminal 102. FIG. 1B shows an exemplaryswitch 100 wherein moveable member 101 is in contact with terminal 102to thereby complete an electrical circuit and to place switch 100 into a“closed” state. Because protruding regions 116 extend outward fromsubstrate 104, protruding regions 116 appropriately form an electricalconnection without requiring contact between substrate layers 104A-Band/or insulating layers 106A-B. This separation between thenon-conducting layers of moveable member 101 and terminal 102 providesan electrical isolation between the two members, which in turn assistsin isolating actuation signals propagating in switch 100 from signalstransmitted by switch 100, as described more fully below.

Referring now to FIGS. 2A-2D, an exemplary process for building a switch100 suitably includes the broad steps of forming insulating andconducting layers on a substrate (FIG. 2A), isolating the moveablemembers and terminals (FIG. 2B), applying a conductive coating to theappropriate portions of the switch (FIG. 2C), and optionally etching orotherwise processing a backside of the substrate to further defineterminals, moveable members and the like (FIG. 2D). The various stepsdescribed in the figures may be implemented using any manufacturing orfabrication techniques, such as those conventionally used for MEMSand/or integrated circuit technologies. Various switch fabricationtechniques are described, for example, in U.S. Pat. No. 6,303,885.

With reference to FIG. 2A, the switch fabrication process suitablybegins by preparing a substrate assembly 200 that includes a substrate104, an insulating layer 106 and a conducting layer. Substrate 104 isany material such as glass, plastic, silicon or the like that is capableof supporting one or more switches 100. In an exemplary embodiment,substrate 104 is formed from doped silicon, and has a thickness on theorder of 35-75 m, although the actual dimensions will vary widely fromembodiment to embodiment. Similarly, the optional dopants provided insubstrate 104 may be selected to improve the connectivity of the switch,and will also vary widely with various embodiments. Substrate 104 may beprepared in any manner, and in an exemplary embodiment is prepared usingconventional Silicon-on-Insulator (SOI) techniques. Insulating layer 106may be formed of any electrically insulating material such as glass,silicon oxide, or the like, and may be placed on or near an exposedsurface of substrate 104 using any technique such as sputtering,deposition or the like. Similarly, conducting layer 108 may be any metalsuch as aluminum, copper, gold or silver, and may be placed according toany technique. In an exemplary embodiment, insulating layer 106 andconducting layer 108 are deposited on substrate 104 using conventionalliquid-phase epitaxy and/or low pressure chemical vapor depositiontechniques, as appropriate.

With reference to FIG. 2B, the various electrically conducting andinsulating regions of switch 100 may be suitably isolated in substrateassembly 200. Conducting layer 108 may be patterned or otherwiseprocessed using conventional etching, lithography or other techniques,for example, to create gaps 201 between separate electrical nodes.Patterning appropriately delineates moveable members 101, actuatingcircuitry, receiving terminals 102 and the like from each other. Anexemplary pattern for a switch 100 is discussed below in conjunctionwith FIG. 3. In alternate embodiments, conducting layer 108 may beeliminated entirely, with conducting and/or insulating regions onsubstrate assembly 200 provided by selective doping of substrate 104, asdescribed more fully below.

Referring now to FIG. 2C, an additional conducting layer 110 of gold oranother appropriate material may be grown, electroplated or otherwiseformed on conducting layer 108. In one embodiment, substrate assembly200 is further formed with an additional non-conducting layer of oxideor the like that is applied after etching or patterning. Electrolessgold or another conductor can then be “grown” or otherwise applied onportions of substrate assembly that are unprotected by the additionalnon-conducting layer. Alternatively, conductive material can beevaporated or sputtered selectively on conductive areas using a shadowmask or the like. In yet another embodiment, gold or another conductivematerial is suitably electroplated, as described in conjunction withFIG. 3 below. In such embodiments conducting layer 108 may not bepresent, with silicon dioxide or another insulator providing electricalinsulation between parts of switch 100 used for electrostatic actuationand parts used for signal conduction. In various embodiments, protrudingregion 116 is formed of conductive material as appropriate to engageother contact members while maintaining electrical isolation betweensubstrate portions 104. Protruding regions 116 may be formed as aconsequence of the additional exposed surface near the corners ofconducting layer 108, for example, or by any other technique.

In a further embodiment, the various components of switch 100 may bephysically separated from each other using conventional MEMS techniques.An anisotropic etchant such as Tetra-Methyl Ammonium Hydrate (TMAH) orPotassium Hydroxide (KOH), for example, may be used to separate moveablemember 101 from terminal 102 as appropriate. In further embodiments (andas shown in FIG. 2D), additional insulating layers 206A,B and/orconducting layers 208A,B may be formed after separation but beforeformation of the outer conducting layer 110 to improve coverage by layer110/210A-B. Such layers may be formed following additional etching orprocessing from the front or back side of substrate 104, as appropriate.Accordingly, the various contact members and other components of switch100 may take any shape or form in a wide variety of alternate butequivalent embodiments.

FIGS. 3 and 4 are top and side views, respectively, of an exemplaryswitch assembly 300, with FIG. 4 being a cross-sectional side view takenalong line A-A′ in FIG. 3. Referring now to FIG. 3, an exemplary switchassembly 300 suitably includes one or more cantilevers or other moveablemembers 101A-B that are capable of interacting with any number ofreceiving terminals 102A-D, as appropriate. In the exemplary switchassembly 300 shown in FIG. 3, two tri-stable switches corresponding tomoveable members 101A and 101B are shown. One switch, for example, has afirst state corresponding to contact between moveable member 101A andterminal 102A, a second state corresponding to contact between moveablemember 101A and terminal 102B, and a third state corresponding to nocontact between moveable member 101A and either terminal. Similarly, theother switch shown has a first state corresponding to contact betweenmoveable member 101B and terminal 102C, a second state corresponding tocontact between moveable member 101B and terminal 102D, and a thirdstate corresponding to no contact between moveable member 101B andeither terminal. Accordingly, each of the two switches are capable ofthree separate output states. Alternate embodiments of switch fabric 300may include any number of moveable members 101 and/or terminals 102.Similarly, each switch may have any number of available output statessuch as two, three or more.

Each moveable member 101 and terminal 102 may be formed from a commonsubstrate 104 as described above, with one or more hinges 304 providingflexible mechanical support for each moveable member 101. Each moveablemember 101A-B suitably includes two conducting regions 312 and 314 thatare capable of electrically interfacing with terminals 102A-D asdescribed above. In the exemplary embodiment shown in FIG. 3, member101A has a first conducting region 314A that interfaces with terminal102A and a second conducting region 314B that interfaces with terminal102B. Similarly, member 101B has a first conducting region 312A thatinterfaces with terminal 102C and a second conducting region 312B thatinterfaces with terminal 102D.

Each moveable member 101 may also include another conducting region 310that may be used to actuate the member 101 between the various states ofswitch 300. In the exemplary embodiment shown in FIG. 3, for example,each conducting region 310 is integrally formed with a comb-type portion316 that is sensitive to electrostatic energy or other stimulus providedby actuators 308A-D. In the exemplary embodiment shown in FIG. 3, eachportion 316 includes a series of comb-like teeth that include metal,permalloy or other material capable of being actuated by one or moreactuators 308A-D. In practice, each moveable member 101 may includemultiple portions 316 that are sensitive to electrostatic force, andportions 316 may take any shape and/or may be located at any point on ornear moveable member 101. Although not shown in FIG. 3 for purposes ofsimplicity, in practice each member 101 may include two or more portions316 on opposing sides of conducting region 310, for example, to increasethe response to applied electrostatic force and to thereby more easilyactuate the member between the various states of switch 300.

In practice, each moveable member 101 is displaced by one or moreactuating circuits 308A-D as appropriate. In the exemplary embodimentshown in FIG. 3, for example, moveable member is suitably displacedtoward terminal 102A by providing an electrostatic charge on actuator308A that attracts comb portion 316. Similarly, an electrostatic chargeprovided by actuator 308B appropriately attracts comb portion 316 towardterminal 102B. Providing an electrostatic charge to both actuators308A-B appropriately attracts comb portion 316 to the central locationsuch that member 101A is electrically separated from each terminal 102Aand 102B to place the switch into an open circuit-type state. Similarlogic could be applied to member 101B, which is appropriately displacedbetween the three states by actuators 308C and 308D. In alternateembodiments, electrostatic attraction could be replaced or supplementedwith electrostatic repulsion, RF signals, inductance of electromagneticsignals, or any other actuating force.

As briefly mentioned above, the various conducting regions 310, 312 and314 are appropriately isolated from each other by electricallyinsulating portions 306, which may be exposed portions of insulatinglayer 106 discussed above, or which may be made up of anadditionally-applied insulating material. Alternatively, insulatingportions 306 (as well as some or all of the conducting portions onswitch assembly 300) may be formed by injecting or otherwise placingdopant materials in the appropriate regions of substrate 104. Inpractice, hinges 304 and conducting regions 312 and 314 may be laid outon substrate 104 (FIGS. 1 and 4) in a pattern that allows for convenientelectroplating. In such embodiments, an electrical charge applied atcontact 302 has electrical continuity through conducting layer 108(FIGS. 1-2) across each hinge 304 and conducting region 312 and 314.When such a charge is applied, outer conducting layer 110 can be readilyelectroplated to the desired locations on switch 300, as appropriate.Insulating regions 306 suitably provide electrical isolation for thoseparts of switch 300 that are not desired to become electroplated,thereby improving the manufacturability of switch 300. Electroplatingmay also provide appropriate protruding regions 116 as described above,and as best seen in FIG. 4.

Electroplating hinges 304 also provides mechanical reinforcement forsupporting moveable members 101, which are appropriately otherwiseisolated from substrate 104 to promote ease of movement. With referencenow to FIG. 4, member 101A is suitably separated from substrate 104 by agap 402 to permit lateral movement toward terminals 102A and 102B asappropriate. Gap 402 may be formed through conventional MEMS techniques,including backside etching or the like. Alternatively, substrate 104 maybe formed with a sacrificial layer 404 that can be etched usingconventional front side etching or otherwise removed to form gap 402. Insuch embodiments, sacrificial layer 402 may be formed of an oxide (e.g.silicon oxide) or another material that may be etched through cavitiesformed in layers 106, 108 and/or 110 as appropriate.

With reference now to FIGS. 5A-C, switch 500 is appropriately held in anumber of stable output states through the use of mechanical energyapplied by one or more receiving terminals. Switch 500 suitably includesat least one moveable member 101 that is displaceable to interface withone or more terminal arms 502, 504, 506, 508. Each terminal arm 502,504, 506, 508 is appropriately designed to be moveable, rotatable,deformable or otherwise displaceable to place switch 500 into differentoutput states. In an exemplary embodiment, each arm 502, 504, 506, 508is designed to bend in an elastic-type fashion about a fixed point 512.Such deformabililty or elasticity may be provided by conventional MEMSor other techniques. In various embodiments, one or more terminal armsare designed to include an outcropping 510 that is able to electricallycommunicate with moveable member 101. In the embodiment shown in FIGS.5A-C, terminal arms 502 and 504 cooperate to provide an electricalconnection with moveable member 101 when the switch is in a first state,and terminal arms 505 and 508 cooperate to provide an electricalconnection with moveable member 101 when the switch is in a secondstate, as shown in FIG. 5C. A third state may be provided when moveablemember 101 is electrically isolated from both sets of terminal arms, asshown in FIG. 5A. The layout and structural components of switch 500appropriately corresponds to those of switches 100, 300 and the likediscussed above, or the concepts described with respect to switch 500may be applied to any type of switch or switch architecture in a widearray of equivalent embodiments. Various equivalent embodiments ofswitch 500 include any number of moveable members 101, terminal arms,terminals, or output states for each moveable member 101. Although notvisible in FIG. 5, each outcropping 510 or any other portion of terminalarms 502, 504, 506 and/or 508 may include a protruding region 116 asdiscussed above to further improve electrical connectivity between theterminal arm and moveable member 101.

Referring to FIG. 5A, switch 500 is shown in an exemplary “open” state(corresponding to an open circuit) whereby moveable member 101 is notelectrically coupled to either set of terminal arms. Terminal arms 502,504, 506 and 508 are appropriately designed such that their natural“biased” state corresponds to the open state wherein the arms areisolated from moveable member 101. As used herein, “biased state” refersto the physical space occupied by one or more terminal arms 502, 504,506, 508 when no actuation force or energy is applied and when no otherobject blocks or prevents natural movement of the terminal arm.

In operation, switch 500 is placed into a different state when moveablemember 101 is moved into the bias position of one or more terminal armssuch that the mechanical force applied by the terminal arm in attemptingto return to the bias state holds the terminal arm in contact withmoveable member 101. In an exemplary embodiment, this movement involvesmoving the terminal arms out of the bias position, moving the moveablemember into the space occupied by the terminal arms in the biasposition, and then releasing the terminal arms to create mechanical andelectrical contact between the arms and moveable member 101. Withreference now to FIG. 5B, terminal arms 506 and 508 are appropriatelyactuated to move outcroppings 510 out of the way so that moveable member101 may be displaced as appropriate. Although this movement is shown inFIG. 5B as a rotation about a fixed pivot point 512 on terminal arms506, 508, alternate embodiments may make use of lateral displacement invertical and/or horizontal directions, or any other type of movement.

After the terminal arms are moved out of the bias position, moveablemember 101 is appropriately actuated to place at least some portion ofmember 101 into the space occupied by at least some portion of terminalarms 506, 508 in the bias position. This actuation may be provided withelectrostatic force as described above and below, or with any otherconventional actuation techniques. In the embodiment shown in FIGS.5A-C, moveable member 101 is laterally displaced using electrostaticforce or the like so that a portion of moveable member 101 occupiesspace corresponding to the bias positions of outcroppings 510 ofterminal arms 506, 508.

As actuating force is removed from terminal arms 506 and 508, potentialenergy stored in the arms is converted to kinetic energy to therebyproduce a torque that attempts to return arms 506, 508 to their biaspositions. Because the bias position is now occupied by moveable member101, however, arms 506 and 508 impact upon member 101 and are suitablyprevented from further movement. Because potential energy remains in thearms until they are placed in the bias position, a mechanical force isprovided that maintains arms 506, 508 against moveable member 101 tothereby hold switch 500 in the closed state (corresponding to a closedcircuit). Accordingly, switch 500 will remain in the closed state eventhough no further electrostatic or other energy is expended. AlthoughFIGS. 5A-C have concentrated on actuation of terminal arms 506 and 508,similar concepts could be employed to actuate terminal arms 502, 504 andto place moveable member 101 in contact with arms 502, 504. Switch 500is therefore capable of several stable output states, and may beconsidered to be a multi-stable switch.

Additional detail about an exemplary actuation scheme is shown in FIG.6. With reference now to FIG. 6, each terminal arm 506, 508 isfabricated with an electrostatic-sensitive area 606 that is receptive toelectrostatic energy provided by actuators 602, 604, respectively.Electrostatic energy from actuators 602, 604 appropriately attracts ametal, permalloy or other material in areas 606 to displace the armsaway from their bias position. Although actuators 602, 604 and areas 606are shown as comb-type actuators in FIG. 6, any time of electrostatic orother actuation could be used in alternate but equivalent embodiments.Similarly, moveable member 101 may be actuated into position using anyactuation technique or structure 308. Although a simple block actuator308 is shown in FIG. 6, in practice moveable member 101 may be displacedwith a comb-type or other actuator such as that discussed in conjunctionwith FIG. 3 above.

In various embodiments, the relative positions of outcropping 510 andareas 606 may be designed so as to increase the amount of leverageapplied by terminal arms 506 and/or 508 upon moveable member 101. In theembodiment shown in FIG. 6, arms 506 and 508 appropriately pivot about arelatively fixed base 512. If the actuation force is applied to the armsat a position on arms 506, 508 that is relatively far from the pivotpoint, the amount of displacement realized from the actuation force canbe increased or maximized. Similarly, by locating outcropping 510 to berelatively nearer to pivot point 510, the amount of leverage applied byarms 506, 508 upon member 101 can be increased. This increase inleverage appropriately provides improved mechanical force to therebymaintain arms 506, 508 in position against member 101, and serves toincrease the efficiency of force applied for a given duration ormagnitude of actuating force. Of course other physical layouts of arms506, 508 and member 101 could be formulated, with outcropping 510 and/orareas 606 being relocated, eliminated or combined in other equivalentembodiments. The efficiency of the actuating force can be furtherincreased by providing a dielectric material in the spaces surroundingand/or in close proximity to actuators 602, 604 and/or areas 606.Examples of dielectric materials that may be present in variousexemplary embodiments include ceramics, polymers (e.g. polyimides orepoxies), silicon dioxide (SiO₂), dielectric liquids and/or any otherorganic or inorganic dielectric material.

Accordingly, there is provided a micro electromagnetic switch that iscapable of providing enhanced electrical connectivity, and that iscapable of remaining in a selected output state even when actuationenergy is no longer provided to the switch. Such switches have numerousapplications across many fields, including medical, aerospace, consumerelectronics, and the like.

While at least one exemplary embodiment has been presented in theforegoing detailed description, it should be appreciated that a vastnumber of variations exist. It should also be appreciated that theexemplary embodiment or exemplary embodiments are only examples, and arenot intended to limit the scope, applicability, or configuration of theinvention in any way. Rather, the foregoing detailed description willprovide those skilled in the art with a convenient road map forimplementing the exemplary embodiment or exemplary embodiments. Itshould be understood that various changes can be made in the functionand arrangement of elements without departing from the scope of theinvention as set forth in the appended claims and the legal equivalentsthereof.

1. A method of forming a micro electromechanical switch on a substrate,the method comprising the steps of: forming an insulating layer on thesubstrate; forming a conducting layer on the insulating layer; isolatingat least one moveable member and at least one receiving terminal of theswitch; and applying a conductive coating to substantially encapsulatethe conducting layer and to form protruding regions extending outwardlyfrom the substrate on the at least one moveable member and the at leastone receiving terminal.
 2. The method of claim 1 further comprising thestep of etching a bottom side of the at least one moveable member. 3.The method of claim 1 further comprising the step of patterning theconducting layer.
 4. The method of claim 3 wherein the applying stepcomprises the step of providing an electric current to the conductinglayer to thereby electroplate the conductive coating on the conductinglayer.
 5. The method of claim 1 wherein the applying step comprisesapplying electroless gold.
 6. A multi-stable electromechanical switchhaving an open state and a closed state, the electromechanical switchcomprising: a moveable member; at least one pair of receiving terminalsbiased to a bias position corresponding to the open state, wherein eachterminal of the at least one pair of receiving terminals is configuredto interface with the moveable member in the closed state; and anactuating circuit configured to provide electrostatic energy and tothereby displace the at least one pair of receiving terminals from thebias position, and to displace the moveable member toward the biasposition; wherein the receiving terminals are further configured toreturn toward the bias position when the electrostatic energy isremoved, and to thereby create an electrical connection with themoveable member, thereby retaining the electromechanical switch in theclosed state.
 7. The electromechanical switch of claim 6 wherein themoveable member comprises a conducting portion having at least oneprotruding region configured to interface with the at least one pair ofreceiving terminals.
 8. The electromechanical switch of claim 6 whereinthe actuating circuit comprises a comb actuator.
 9. Theelectromechanical switch of claim 6 wherein the at least one pair ofreceiving terminals comprises two pairs of receiving terminals, andwherein the closed state of each of the two pairs of receiving terminalscorresponds to a different state of the electromechanical switch. 10.The electromechanical switch of claim 6 wherein each of the at least onepair of receiving terminals comprises an outcropping configured tocontact with the moveable member.
 11. The electromechanical switch ofclaim 6 further comprising a dielectric material located in proximity tothe actuating circuit.
 12. A method of switching an electromechanicalswitch from an open state to a closed state, the method comprising thesteps of: displacing a pair of receiving terminals from a biasedposition corresponding to the open state; moving a moveable memberbetween the pair of receiving terminals to thereby occupy at least aportion of the biased position; and discontinuing the electrostaticenergy to thereby allow the pair of receiving terminals to return towardthe biased position, and to thereby place the pair of receivingterminals in contact with the moveable member, thereby placing theelectromechanical switch in the closed position.
 13. The method of claim12 wherein the displacing step and the moving step are executed at leastin part with electrostatic energy.
 14. A multi-stable electromechanicalswitch having a moveable member and a pair of receiving terminals, theelectromechanical switch comprising: means for displacing the pair ofreceiving terminals from a biased position corresponding to the openstate; means for moving the moveable member between the pair ofreceiving terminals to thereby occupy at least a portion of the biasedposition; and means for discontinuing the electrostatic energy tothereby allow the pair of receiving terminals to return toward thebiased position, and to thereby place the pair of receiving terminals incontact with the moveable member, thereby placing the electromechanicalswitch in the closed position.